Suspension system

Abstract

To improve ride comfort at the time when a vehicle passes through a step.SOLUTION: A control device of a suspension system is configured to: estimate a tactile-sense wheel that is a wheel brought into contact with a step at the earliest time among a plurality of wheels, on the basis of vehicle information including a steering angle of the vehicle; bring damping force of a shock absorber corresponding to the tactile-sense wheel into a soft state where the force is smaller than a predetermined threshold and bring damping force of all shock absorbers corresponding to the wheels other than the tactile-sense wheel into a hard state where the force is larger than the damping force in the soft state, when the tactile-sense wheel is brought into contact with the step; derive a contact wheel that is a wheel brought into contact with the step after the tactile-sense wheel is brought into contact with the step, on the basis of an estimated result of the tactile-sense wheel and the vehicle information; and bring damping force of the shock absorber corresponding to the contact wheel into the soft state, and bring damping force of all shock absorbers corresponding to the wheels other than the contact wheel into the hard state, when the contact wheel is brought into contact with the step.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a suspension system. [Background technology]

[0002] In suspension systems that allow the damping force, which converges the vibration of springs installed between the wheels and the vehicle body, to be adjusted according to the situation, technology is used to optimize the damping force when the wheels go over bumps. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5093507 [Patent Document 2] JP 2012-51424 A Summary of the Invention [Problem to be solved by the invention]

[0004] When multiple wheels pass over a step at different times, it is necessary to individually optimize the damping force of the wheel passing over the step and the damping forces of the other wheels; however, conventional technology may not be able to sufficiently optimize the damping force of each wheel.

[0005] The present invention has been made in consideration of the above, and provides a suspension system that can improve the ride comfort when passing over a step. [Means for solving the problem]

[0006] One embodiment of the suspension system comprises a plurality of shock absorbers installed between each of a plurality of wheels and a vehicle body, each of which generates a damping force that converges the stroke of the suspension device, and a control device capable of individually controlling the damping force of the plurality of shock absorbers.The control device estimates a tactile wheel, which is the wheel among the plurality of wheels that will come into contact with a step first, based on vehicle information including the steering angle of the vehicle, and when the tactile wheel contacts the step, sets the damping force of the shock absorber corresponding to the tactile wheel to a soft state that is smaller than a predetermined threshold value, and sets the damping force of all shock absorbers corresponding to wheels other than the tactile wheel to a hard state that is larger than the soft state.Based on the estimation result of the tactile wheel and the vehicle information, the control device derives a contact wheel, which is the wheel that will come into contact with the step after the tactile wheel contacts the step, and when the contact wheel contacts the step, sets the damping force of the shock absorber corresponding to the contact wheel to a soft state, and sets the damping force of all shock absorbers corresponding to wheels other than the contact wheel to the hard state. Effect of the Invention

[0007] According to the suspension system of the present invention, when multiple wheels pass over a step at different times, the damping force of the shock absorber corresponding to the wheel passing over the step is in a soft state, and the damping force of the shock absorbers corresponding to the other wheels is in a hard state. This makes it possible to sufficiently absorb the impact from the step and to suppress excessive stroke of the suspension devices corresponding to the wheels other than the wheel passing over the step, thereby improving the ride comfort when passing over the step. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a vehicle equipped with a suspension system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of the suspension device according to the first embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of a configuration related to control of the shock absorber in the suspension system of the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of a functional configuration of the ECU according to the first embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of a situation when the haptic ring of the first embodiment overcomes a step. [Figure 6] FIG. 6 is a diagram showing an example of a situation when the contact wheel of the first embodiment overcomes a step. [Figure 7] FIG. 7 is a diagram showing an example of a relationship between the run-on wheel and the damping force of each shock absorber in the first embodiment. [Figure 8] FIG. 8 is a flowchart illustrating an example of processing by the ECU according to the first embodiment. [Figure 9] FIG. 9 is a flowchart illustrating an example of processing by the ECU according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Exemplary embodiments of the present invention are disclosed below. The configurations of the embodiments described below, and the actions, results, and effects brought about by the configurations are merely examples. The present invention can be realized with configurations other than those disclosed in the following embodiments, and it is possible to obtain at least one of various effects based on the basic configurations and derivative effects.

[0010] (First embodiment) 1 is a diagram showing an example of the configuration of a vehicle 1 equipped with a suspension system S of the first embodiment. The vehicle 1 illustrated here is a four-wheeled automobile capable of running on a road surface, and includes a vehicle body 2 and four wheels 3 (a left front wheel 3FL, a right front wheel 3FR, a left rear wheel 3RL, and a right rear wheel 3RR). Hereinafter, the left front wheel 3FL, the right front wheel 3FR, the left rear wheel 3RL, and the right rear wheel 3RR may be referred to as wheels 3.

[0011] The suspension system S of this embodiment includes four suspension devices 11FL, 11FR, 11RL, and 11RR, three acceleration sensors 12I, 12L, and 12R, and an ECU (Electronic Control Unit) 13.

[0012] The suspensions 11FL, 11FR, 11RL, and 11RR are devices for reducing impacts from the road surface to the vehicle body 2, and are provided to correspond to the left front wheel 3FL, the right front wheel 3FR, the left rear wheel 3RL, and the right rear wheel 3RR, respectively. Each suspension 11FL, 11FR, 11RL, and 11RR includes springs 21FL, 21FR, 21RL, and 21RR and shock absorbers 22FL, 22FR, 22RL, and 22RR. That is, the suspension 11FL corresponding to the left front wheel 3FL includes a spring 21FL and a shock absorber 22FL, the suspension 11FR corresponding to the right front wheel 3FR includes a spring 21FR and a shock absorber 22FR, the suspension 11RL corresponding to the left rear wheel 3RL includes a spring 21RL and a shock absorber 22RL, and the suspension 11RR corresponding to the right rear wheel 3RR includes a spring 21RR and a shock absorber 22RR. Hereinafter, the suspensions 11FL, 11FR, 11RL, and 11RR may be referred to as suspensions 11. The springs 21FL, 21FR, 21RL, and 21RR may be referred to as springs 21. The shock absorbers 22FL, 22FR, 22RL, and 22RR may be referred to as shock absorbers 22.

[0013] The acceleration sensors 12I, 12L, 12R are sensors that detect the sprung acceleration of the vehicle 1, i.e., the acceleration of the vertical movement of the vehicle body 2 above the suspension system 11. In this embodiment, the acceleration sensors used are a built-in acceleration sensor 12I built into the ECU 13 installed at the rear of the vehicle body 2, a left acceleration sensor 12L installed on the left side of the front part of the vehicle body 2, and a right acceleration sensor 12R installed on the right side of the front part of the vehicle body 2. Hereinafter, the built-in acceleration sensor 12I, the left acceleration sensor 12L, and the right acceleration sensor 12R may be referred to as acceleration sensors 12. Note that the number and installation positions of the acceleration sensors 12 are not limited to those described above.

[0014] Fig. 2 is a diagram showing an example of the configuration of the suspension device 11 of the first embodiment. Fig. 2 shows a schematic configuration of one suspension device 11 provided between one wheel 3 and the vehicle body 2. The suspension device 11 has a spring 21 and a shock absorber 22. All four suspension devices 11 have the same configuration.

[0015] The spring 21 is interposed between the wheel 3 and the vehicle body 2, and is a member that expands and contracts to absorb shock from the road surface to the vehicle body 2, and generates a reaction force (restoring force) according to the state of expansion and contraction.

[0016] The shock absorber 22 is a device that generates a damping force that converges the vibration (expansion and contraction movement) of the spring 21, i.e., the stroke of the suspension device 11. The damping force of the shock absorber 22 is changeable in response to a control signal (control current) from the ECU 13. The specific configuration of the shock absorber 22 is not particularly limited, but may be, for example, a configuration that utilizes a hydraulic damper whose damping force changes in response to fluid pressure, an actuator that operates to change the fluid pressure of the hydraulic damper in response to the control current from the ECU 13, or the like.

[0017] 3 is a diagram showing an example of a configuration related to the control of the shock absorber 22 in the suspension system S of the first embodiment. The ECU 13 of this embodiment controls each of the shock absorbers 22FL, 22FR, 22RL, and 22RR based on various information acquired from the acceleration sensor 12, a CAN (Controller Area Network), and the like. The various information includes the sprung acceleration near the rear of the vehicle 1 detected by the built-in acceleration (G) sensor 12I, the sprung acceleration on the front left side of the vehicle 1 detected by the left acceleration sensor 12L, the sprung acceleration on the front right side of the vehicle 1 detected by the right acceleration sensor 12R, and vehicle information acquired from the CAN. The vehicle information may include, for example, the steering angle of the vehicle 1, map information, vehicle position information (GPS information, etc.), traveling direction, vehicle speed, longitudinal acceleration, lateral acceleration, yaw rate, and information on objects present around the vehicle 1.

[0018] The ECU 13 of the present embodiment has a function for optimizing the damping force of each of the shock absorbers 22FL, 22FR, 22RL, and 22RR when the vehicle 1 passes over a step.

[0019] 4 is a diagram showing an example of the functional configuration of the ECU 13 of the first embodiment. The ECU 13 of this embodiment includes a tactile wheel estimation unit 101, a contact wheel derivation unit 102, a contact detection unit 103, and a damping force control unit 104. These functional units may be configured by cooperation between hardware elements and software elements (programs, etc.) that configure the ECU 13. Furthermore, at least one of these functional units may be configured by dedicated hardware (circuits, etc.).

[0020] The haptic wheel estimation unit 101 estimates the haptic wheel, which is the wheel 3 that contacts the step first among the four wheels 3, based on vehicle information including the steering angle of the vehicle 1. The specific method of estimating the haptic wheel should not be particularly limited, but for example, the haptic wheel can be estimated based on the steering angle, map information, vehicle position information, etc. By using such vehicle information, for example, it is possible to detect the operation of the vehicle 1 traveling on the roadway turning left and proceeding into an area without a roadway (for example, the operation of entering a parking lot of a store from the roadway across the sidewalk, etc.), and when such an operation is detected, it is possible to estimate that the left front wheel 3FL will be the haptic wheel. Note that the method of estimating the haptic wheel is not limited to this, and for example, it is also possible to detect the position of the step based on information acquired from an in-vehicle camera, an obstacle sensor, etc., and estimate the haptic wheel based on the detection result and the steering angle.

[0021] The contact detection unit 103 detects, based on the acceleration detected by the acceleration sensor 12, that the tactile ring estimated by the tactile ring estimation unit 101 has come into contact with a step.

[0022] When the haptic wheel contacts a step, the damping force control unit 104 sets the damping force of the shock absorber 22 corresponding to the haptic wheel to a soft state smaller than a predetermined threshold value, and sets the damping force of all shock absorbers 22 corresponding to the wheels 3 other than the haptic wheel to a hard state larger than the soft state. The soft state can be, for example, a full soft state in which the damping force is the smallest. The hard state can be, for example, a full hard state in which the damping force is the largest, or a variable hard state in which the damping force is changed according to the road input within a range larger than a predetermined threshold value. By setting the damping force to the full hard state, unnecessary vibrations of the vehicle body 2 can be quickly suppressed. Furthermore, by setting the damping force to the variable hard state, unnecessary vibrations of the vehicle body 2 can be suppressed and vibrations due to the undulations of the road surface can be absorbed at the same time.

[0023] The contact wheel derivation unit 102 derives a contact wheel, which is the wheel 3 that comes into contact with the step after the tactile wheel comes into contact with the step, based on the estimation result of the tactile wheel by the tactile wheel estimation unit 101 and the vehicle information. The specific method of deriving the contact wheel should not be particularly limited, but for example, the contact wheel can be derived based on the movement trajectory (steering angle, etc.) of the vehicle 1 after the tactile wheel comes into contact with the step, the position of the step, etc. Note that the method of deriving the contact wheel is not limited to this. In addition, the contact wheel derivation unit 102 may estimate the contact timing at which the contact wheel comes into contact with the step, based on the vehicle information, etc. The specific method of estimating the contact timing should not be particularly limited, but for example, the contact timing can be estimated based on the movement trajectory, speed, position of the step, etc. of the vehicle 1.

[0024] The contact detection unit 103 detects that the contact wheel derived by the contact wheel derivation unit 102 has come into contact with a step, based on the acceleration detected by the acceleration sensor 12. At this time, by referring to the contact timing estimated in advance by the contact wheel derivation unit 102, it is possible to improve the detection accuracy of the contact of the contact wheel with a step.

[0025] When a contact wheel derived by the contact wheel lead-out portion 102 comes into contact with a step, the damping force control portion 104 sets the damping force of the shock absorber 22 corresponding to the contact wheel to a soft state, and sets the damping forces of all shock absorbers 33 corresponding to wheels 3 other than the contact wheel to a hard state.

[0026] Furthermore, during normal driving (when not passing over a step, etc.), the damping force control unit 104 performs control (e.g., skyhook control) to optimize the damping force of each shock absorber 22 in response to a road input from each wheel 3. The road input may be, for example, the stroke speed of the shock absorber 22.

[0027] Fig. 5 is a diagram showing an example of a situation when the tactile ring of the first embodiment goes over a step 31. Fig. 5 illustrates a situation in which the vehicle 1 is turning left from the roadway R and about to go over a step 31 (for example, a slope on a sidewalk). In such a situation, the tactile ring estimation unit 101 estimates that the left front wheel 3FL is a tactile ring based on vehicle information including the steering angle, etc.

[0028] When the contact detection unit 103 detects that the left front wheel 3FL, which is a haptic wheel, has come into contact with the step 31, the damping force control unit 104 sets the shock absorber 22FL of the left front wheel 3FL to a soft state and sets the shock absorbers 22FR, 22FL, and 22RR of the other wheels 3FR, 3RL, and 3RR to a hard state. As a result, when the left front wheel 3FL goes over the step 31, the spring 21FL of the left front wheel 3FL sufficiently absorbs the impact from the step 31, and vibrations caused by the springs 21FR, 21RL, and 21RR of the other wheels 3FR, 3RL, and 3RR are sufficiently suppressed. This improves the ride comfort when the left front wheel 3FL goes over the step 31.

[0029] Fig. 6 is a diagram showing an example of a situation when the contact wheel of the first embodiment goes over a step 31. Fig. 6 illustrates a situation in which the right front wheel 3FR is about to go over the step 31 after the left front wheel 3FL, which is a tactile wheel, has gone over the step 31. At this time, the contact wheel deriving unit 102 derives that the right front wheel 3FR is a contact wheel based on the estimation result of the tactile wheel by the tactile wheel estimation unit 101 and vehicle information. The contact wheel deriving unit 102 may also estimate the contact timing at which the contact wheel (right front wheel 3FR) comes into contact with the step 31 based on information such as the steering angle and vehicle speed.

[0030] When the contact detection unit 103 detects that the right front wheel 3FR, which is the contact wheel, has come into contact with the step 31, the damping force control unit 104 sets the shock absorber 22FR of the right front wheel 3FR to a soft state and sets the shock absorbers 22FL, 22RL, and 22RR of the other wheels 3FL, 3RL, and 3RR to a hard state. At this time, by referring to the contact timing estimated in advance by the contact wheel derivation unit 102, the contact of the right front wheel 3FR, which is the contact wheel, with the step 31 can be detected with high accuracy. As a result, when the right front wheel 3FR goes over the step 31, the impact from the step 31 is sufficiently absorbed by the spring 21FR of the right front wheel 3FR, and vibrations caused by the springs 21FL, 21RL, and 21RR of the other wheels 3FL, 3RL, and 3RR are sufficiently suppressed. As a result, the ride comfort when the right front wheel 3FR goes over the step 31 can be improved.

[0031] The above control changes according to the change in the contact wheel. After the right front wheel 3FR goes over the step 31, the contact wheel shifts in the order of the left rear wheel 3RL → the right rear wheel 3RR. In this case, when the left rear wheel 3RL comes into contact with the step 31, the shock absorber 22RL of the left rear wheel 3RL is set to a soft state, and the shock absorbers 22FL, 22FR, 22RR of the other wheels 3FL, 3FR, 3RR are set to a hard state. Also, when the right rear wheel 3RR comes into contact with the step 31, the shock absorber 22RR of the right rear wheel 3RR is set to a soft state, and the shock absorbers 22FL, 22FR, 22RL of the other wheels 3FL, 3FR, 3RL are set to a hard state. This improves the ride comfort when the left rear wheel 3RL and the right rear wheel 3RR go over the step 31.

[0032] FIG. 7 is a diagram showing an example of the relationship between the run-on wheels and the damping forces of the shock absorbers 22 in the first embodiment. The run-on wheels refer to the wheels 3 that are running on or about to run on the step 31. "-" refers to a state in which none of the wheels 3 are running on the step 31. "S" refers to a state in which the damping force of the shock absorbers 22 is in a soft state. "H" refers to a state in which the damping force of the shock absorbers 22 is in a hard state. "F" refers to a state in which the damping force of the shock absorbers 22 is in a normal control state (for example, skyhook control based on road surface input). Here, a case is illustrated in which the haptic wheel is the left front wheel 3FL, and the contact wheel shifts in the order of the right front wheel 3FR → left rear wheel 3RL → right rear wheel 3RR.

[0033] As shown in Fig. 7, before the left front wheel 3FL, which is a haptic wheel, comes into contact with the step 31, all the shock absorbers 22 are in the normal control state. Thereafter, when the left front wheel 3FL, which is a haptic wheel, becomes a run-on wheel, i.e., when the left front wheel 3FL comes into contact with the step 31, the shock absorber 22FL of the left front wheel 3FL goes into the soft state, and the shock absorbers 22FR, 22RL, 22RR of the other wheels 3FR, 3RL, 3RR go into the hard state. At this time, only the contraction side damping force of the shock absorber 22FL of the left front wheel 3FL (the force that returns the contracted spring 21FL) may be in the soft state, and the extension side damping force (the force that returns the expanded spring 21FL) may be in the normal state.

[0034] After that, when the left front wheel 3FL goes over the step 31 and all the wheels 3 are not run-on wheels (not in contact with the step 31), all the shock absorbers 22 are in the normal control state. After that, when the right front wheel 3FR becomes a run-on wheel, that is, when the right front wheel 3FR comes into contact with the step 31, the shock absorber 22FR of the right front wheel 3FR is in the soft state, and the shock absorbers 22FL, 22RL, 22RR of the other wheels 3FL, 3RL, 3RR are in the hard state. At this time, only the damping force on the contraction side of the shock absorber 22FR of the right front wheel 3FR may be in the soft state, and the damping force on the extension side may be in the normal state.

[0035] After that, when the right front wheel 3FR goes over the step 31 and all the wheels 3 are no longer run-over wheels, all the shock absorbers 22 are in the normal control state. After that, when the left rear wheel 3RL becomes a run-over wheel, that is, when the left rear wheel 3RL comes into contact with the step 31, the shock absorber 22RL of the left rear wheel 3RL is in the soft state, and the shock absorbers 22FL, 22FR, 22RR of the other wheels 3FL, 3FR, 3RR are in the hard state. At this time, only the damping force on the contraction side of the shock absorber 22RL of the left rear wheel 3RL may be in the soft state, and the damping force on the extension side may be in the normal state.

[0036] After that, when the left rear wheel 3RL goes over the step 31 and all the wheels 3 are no longer run-over wheels, all the shock absorbers 22 are in the normal control state. After that, when the right rear wheel 3RR becomes a run-over wheel, that is, when the right rear wheel 3RR comes into contact with the step 31, the shock absorber 22RR of the right rear wheel 3RR is in the soft state, and the shock absorbers 22FL, 22FR, 22RL of the other wheels 3FL, 3FR, 3RL are in the hard state. At this time, only the damping force on the contraction side of the shock absorber 22RR of the right rear wheel 3RR may be in the soft state, and the damping force on the extension side may be in the normal state.

[0037] 8 is a flowchart showing an example of processing by the ECU 13 of the first embodiment. In step S101, the tactile wheel estimation unit 101 determines whether or not the vehicle 1 is proceeding toward the step 31 based on the vehicle information. This determination may be performed based on, for example, the steering angle, map information, vehicle position information, and the like included in the vehicle information. If the vehicle 1 is not proceeding toward the step 31 (S101: No), this routine ends.

[0038] In step S101, if the vehicle 1 is proceeding toward the step 31 (S101: Yes), in step S102, the haptic ring estimation unit 101 estimates which of the four wheels 3 will become the haptic ring based on the vehicle information. Then, in step S103, the contact detection unit 103 determines whether or not the contact of the haptic ring with the step 31 is detected. In step S103, if the contact of the haptic ring with the step 31 is not detected (S103: No), step S103 is executed again. That is, the process waits until the haptic ring comes into contact with the step 31.

[0039] In step S103, if contact of the haptic ring with the step 31 is detected (S103: Yes), in step S104, the damping force control unit 104 sets the shock absorbers 22 of the haptic ring to a soft state and the shock absorbers 22 of the other wheels 3 to a hard state.

[0040] Then, in step S105, the contact wheel derivation unit 102 derives a contact wheel based on the tactile wheel estimation result by the tactile wheel estimation unit 101 and the vehicle information. If a contact wheel is not derived in step S105 (S105: No), in step S110, the damping force control unit 104 executes normal control for the shock absorbers 22 of all wheels 3, and the processes from step S105 onwards are executed again.

[0041] If a contact wheel is derived in step S105 (S105: Yes), in step S106, the contact wheel derivation unit 102 estimates the contact timing at which the contact wheel comes into contact with the step 31 based on vehicle information and the like. Then, in step S107, the contact detection unit 103 determines whether or not contact of the derived contact wheel with the step 31 is detected. If contact of the contact wheel with the step 31 is not detected in step S107 (S107: No), step S107 is executed again. That is, the process waits until the contact wheel comes into contact with the step 31.

[0042] In step S107, if contact of the contact wheel with the step 31 is detected (S107: Yes), in step S108, the damping force control unit 104 puts the shock absorber 22 of the contact wheel into a soft state and the shock absorbers 22 of the other wheels 3 into a hard state.

[0043] Thereafter, in step S109, the contact wheel derivation unit 102 determines whether or not all the wheels 3 have passed over the step 31, and ends this routine if all the wheels 3 have passed over the step 31 (S109: Yes). In step S109, if all the wheels 3 have not passed over the step 31 (S109: No), the processing from step S105 onwards is executed again.

[0044] As described above, according to this embodiment, when multiple wheels 3 pass over a step 31 at different times, the damping force of the shock absorber 22 corresponding to the wheel 3 passing over the step 31 is in a soft state, and the damping force of the shock absorbers 22 corresponding to the other wheels 3 is in a hard state. This makes it possible to sufficiently absorb the impact from the step 31 and to suppress excessive stroke of the suspension devices 11 corresponding to the wheels 3 other than the wheel 3 passing over the step 31, thereby improving the ride comfort when passing over the step 31.

[0045] In addition, since each wheel 3 can be appropriately switched between a hard state and a soft state depending on the transition of the contact wheel, an excellent ride comfort can be achieved even when there are multiple consecutive bumps 31.

[0046] Other embodiments will be described below, but descriptions of parts that are the same as or similar to the first embodiment will be omitted as appropriate.

[0047] Second embodiment In the first embodiment, the damping force of the tactile ring or wheels 3 other than the tactile ring was uniformly set to a hard state, whereas in the second embodiment, the hard state of the tactile ring or wheels 3 other than the tactile ring is changed depending on the condition of the road surface.

[0048] The damping force control unit 104 of this embodiment sets the damping force of the shock absorber 22 corresponding to the wheel 3 other than the tactile wheel to the variable hard state when a predetermined rough road condition indicating that the road surface is rough is satisfied after the tactile wheel contacts the step 31, and sets the shock absorber 33 corresponding to the wheel 3 other than the tactile wheel to the full hard state when the rough road condition is not satisfied. In addition, the damping force control unit 104 of this embodiment sets the damping force of the shock absorber 22 corresponding to the wheel 3 other than the contact wheel to the variable hard state when the rough road condition is satisfied after the contact wheel is derived, and sets the damping force of the shock absorber 22 corresponding to the wheel 3 other than the contact wheel to the full hard state when the rough road condition is not satisfied. The variable hard state is a state in which the damping force is changed according to the road surface input within a range larger than a predetermined threshold value. The full hard state is a state in which the damping force is set to the maximum value. The rough road conditions should be set appropriately depending on the specifications of the vehicle 1, and may be set, for example, based on the amount of fluctuation or variation in the road surface input (for example, the stroke speed of the shock absorber 22, etc.).

[0049] 9 is a flowchart showing an example of processing by the ECU 13 in the second embodiment. In step S201, the tactile wheel estimation unit 101 determines, based on the vehicle information, whether or not the vehicle 1 is proceeding toward the step 31. If the vehicle 1 is not proceeding toward the step 31 (S201: No), this routine ends.

[0050] In step S201, if the vehicle 1 is proceeding toward the step 31 (S201: Yes), in step S202, the haptic ring estimation unit 101 estimates which of the four wheels 3 will become the haptic ring based on the vehicle information.

[0051] Then, in step S203, the contact detection unit 103 determines whether or not contact of the tactile ring with the step 31 has been detected. If contact of the tactile ring with the step 31 has not been detected in step S203 (S203: No), step S203 is executed again. That is, the process waits until the tactile ring comes into contact with the step 31.

[0052] If the contact of the haptic wheel with the step 31 is detected in step S203 (S203: Yes), in step S204, the damping force control unit 104 judges whether or not the rough road condition is satisfied based on the road surface input etc. acquired after the estimation of the haptic wheel. If the rough road condition is satisfied in step S204 (S204: Yes), the damping force control unit 104 sets the shock absorber 22 of the haptic wheel to the soft state and the shock absorber 22 of the other wheels 3 to the variable hard state. On the other hand, if the rough road condition is not satisfied in step S204 (S204: No), the damping force control unit 104 sets the shock absorber 22 of the haptic wheel to the soft state and the shock absorber 22 of the other wheels 3 to the full hard state.

[0053] Then, in step S207, the contact wheel derivation unit 102 derives a contact wheel based on the tactile wheel estimation result by the tactile wheel estimation unit 101 and the vehicle information. If a contact wheel is not derived in step S207 (S207: No), in step S213, the damping force control unit 104 executes normal control for the shock absorbers 22 of all wheels 3, and the processes from step S207 onwards are executed again.

[0054] In step S207, when a contact wheel is derived (S207: Yes), in step S208, the contact wheel derivation unit 102 estimates the contact timing at which the contact wheel comes into contact with the step 31 based on the vehicle information and the like.

[0055] After that, in step S209, the contact detection unit 103 judges whether or not the contact of the derived contact wheel with the step 31 is detected. In step S209, if the contact of the contact wheel with the step 31 is not detected (S209: No), step S209 is executed again. That is, the process waits until the contact wheel comes into contact with the step 31.

[0056] If the contact of the contacting wheel with the step 31 is detected in step S209 (S209: Yes), in step S210 the damping force control unit 104 judges whether or not the rough road condition is satisfied based on the road surface input etc. acquired after the derivation of the contacting wheel. If the rough road condition is satisfied in step S210 (S210: Yes), the damping force control unit 104 sets the shock absorber 22 of the contacting wheel to the soft state and the shock absorbers 22 of the other wheels 3 to the variable hard state. On the other hand, if the rough road condition is not satisfied in step S210 (S210: No), the damping force control unit 104 sets the shock absorber 22 of the contacting wheel to the soft state and the shock absorbers 22 of the other wheels 3 to the full hard state.

[0057] Thereafter, in step S214, the contact wheel derivation unit 102 determines whether or not all the wheels 3 have passed over the step 31, and ends this routine if all the wheels 3 have passed over the step 31 (S214: Yes). If all the wheels 3 have not passed over the step 31 in step S214 (S214: No), the processing from step S207 onwards is executed again.

[0058] As described above, according to this embodiment, when the road surface is rough, the shock absorbers 22 corresponding to the tactile wheels or the wheels 3 other than the tactile wheels are in the variable hard state. This makes it possible to both suppress excessive strokes of the suspension devices 11 corresponding to the wheels 3 other than the wheel 3 passing over the step 31 and absorb shocks on the rough road surface.

[0059] The program for causing a computer (e.g., ECU 14, etc.) to realize the functions of the suspension system S of the above embodiment may be configured to be provided by being recorded in an installable or executable format on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a digital versatile disk (DVD).

[0060] The program may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. The program may be provided or distributed via a network such as the Internet.

[0061] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0062] 1...vehicle, 2...vehicle body, 3...wheel, 11...suspension device, 12...acceleration sensor, 13...ECU, 21...spring, 22...shock absorber, 101...tactile wheel estimation unit, 102...contact wheel derivation unit, 103...contact detection unit, 104...damping force control unit, S...suspension system

Claims

1. a plurality of shock absorbers each installed between a plurality of wheels and a vehicle body, each of which generates a damping force for converging a stroke of a suspension device; A control device capable of individually controlling the damping forces of the plurality of shock absorbers; Equipped with The control device includes: A haptic wheel that is a wheel that contacts a step earliest among the plurality of wheels is estimated based on vehicle information including a steering angle of the vehicle; When the haptic ring comes into contact with the step, the damping force of the shock absorber corresponding to the haptic ring is set to a soft state that is smaller than a predetermined threshold value, and the damping forces of all the shock absorbers corresponding to the wheels other than the haptic ring are set to a hard state that is larger than the soft state, deriving a contact wheel, which is a wheel that comes into contact with the step after the haptic ring comes into contact with the step, based on the estimation result of the haptic ring and the vehicle information; when the contact wheel comes into contact with the step, the damping force of the shock absorber corresponding to the contact wheel is set to the soft state, and the damping forces of all the shock absorbers corresponding to the wheels other than the contact wheel are set to the hard state. Suspension system.

2. The hard state is a full hard state in which the damping force is a maximum value. The suspension system of claim 1 .

3. The hard state is a variable hard state in which the damping force is changed in response to a road surface input within a range greater than a predetermined threshold value. The suspension system of claim 1 .

4. The control device includes: When a predetermined rough road condition indicating that the road surface is rough is satisfied after the haptic wheel comes into contact with the step, the damping force of the shock absorber corresponding to the wheels other than the haptic wheel is changed to a variable hard state in which the damping force of the shock absorber corresponding to the wheels other than the haptic wheel is changed within a range larger than a predetermined threshold value in response to a road surface input, and when the rough road condition is not satisfied, the damping force of the shock absorber corresponding to the wheels other than the haptic wheel is changed to a full hard state in which the damping force of the shock absorber corresponding to the wheels other than the haptic wheel is set to a maximum value; After the contact wheel is derived, if the rough road condition is satisfied, the damping force of the shock absorber corresponding to the wheels other than the contact wheel is set to the variable hard state, and if the rough road condition is not satisfied, the damping force of the shock absorber corresponding to the wheels other than the contact wheel is set to the full hard state. The suspension system of claim 1 .

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